This invention relates generally to a transporting apparatus and, more particularly, to belt turn conveyors, which extend around a curve.
Belt turn conveyors are capable of interconnecting generally straight conveyor sections and provide a turn of up to 180.degree.. Such turn conveyors conventionally includes a pair of conical shaped pulleys, one at each end, and a continuous belt having a smaller length at the inner radius of the turn and a longer length toward the outer radius of the turn. The pulleys and belt are supported by a frame. A conveyor frame typically includes radially spaced legs and horizontal members connecting the legs, which provide a planar support surface for the upper portion of the belt. In operation, especially when the belt is laden with packages or articles to be transported, the belt experiences radial forces, which tend to pull the belt off the pulleys inward of the frame and to cause the belt to ride up against the support frame. Means are provided to retain the belt on the turn conveyor.
In U.S. Pat. No. 4,955,466 to Almes et al., the conveyor belt is provided with an enlarged distal edge (3), which is captured between upper and lower rollers. The rollers are angled so that they bear on an inner, downwardly sloping side of the enlarged edge of the belt and make a line contact with the enlarged edge. Under high speeds of operation, the enlarged edge (3) may tend to distort and flatten so that the belt is not adequately restrained in the vertical direction.
In U.S. Pat. No. 5,332,082 to Sommerfield, a conveyor turn is disclosed which includes a plurality of roller assemblies that are secured to the belt and engage a guide surface provided by a slotted guide rail (31). The vertical movement of the belt is not restrained at its upper portion; instead, the belt is free to lift off the horizontal support member (32) until it makes contact with the free edge of the slotted guide rail. The belt may be subject to increased wear and may experience a shortened operational life.
To overcome the problem of the belt lifting off its support, some conveyors have employed two sets of wheels, one set restrains the belt from sliding off the support and the other set restrains the belt from lifting off the support. For example, in German Document Patent No. DE 41 13 051 C2 discloses two sets of wheel assemblies. However, the supporting structure, which provided the guide rails for the wheels is complicated and generally increases the overall height of the turn conveyor. Furthermore, the spacing between the turn conveyor and the adjacent straight conveyor section is increased in order to accommodate the wheels assemblies and the wheel guide tracks. When the space between the adjacent conveyor sections is increased, smaller packages may fall between the adjacent conveyor sections or may get caught between he sections. Moreover, with the increase in number of wheel assemblies there is a significant increase in noise.
Known belt turn conveyors also tend to have a poor utilization rate because maintenance is difficult and time-consuming when required. This is especially the case with replacement of the belt which has required disassembly of virtually the entire conveyor section. Additionally, difficult alignment procedures have added to the downtime of the conveyor undergoing maintenance or installation.
Therefore, there is a need for a belt turn conveyor which provides means for restraining the belt from lifting off the conveyor support while minimizing the space between adjacent belt conveyor sections and the overall height of the belt turn conveyor and which will reduce the noise of the conveyor when the belt run conveyor is operation. Furthermore, there is a need for a belt that is relatively easy to install and replace.